Pathoanatomy: (The Problem)
Several events can cause the meniscus to become damaged. Acutely, it can tear or rip as a result of too great a force pinching it between the femur and the tibia. Most frequently this is a twisting-type force and unfortunately, is relatively common in sports-related knee injuries. Occasionally it is associated with a ligament rupture as will be discussed later. It does not always require a major fall or twist to cause a meniscal tear. Some occur with nothing more than getting up from a squatting position. Certain meniscal tears occur gradually over a long period of time. In older patients these may represent so-called degenerative meniscal tears and may not be symptomatic. An important aspect of meniscal tears is their location within the meniscus as this may determine the type of treatment which is most appropriate.

Symptoms and Signs: (What it feels like)
An acute meniscal tear may actually be heard as a pop and felt as a tear or rip in the knee. Many are followed within a few minutes to hours by swelling of the knee as a result of blood accumulation. Not all tears are this dramatic. Some do not result in much swelling and some present themselves in a less acute fashion. Patients with meniscal tears often describe a “popping” or “catching” in their knee. Some actually can feel something “out of place”. In the most dramatic situations the knee will actually “lock”, preventing the patient from fully extending or straightening the knee — or occasionally from flexing or bending it. The pain or discomfort is usually along the joint line or where the femur and tibia bone come together. It often starts out relatively painful; then with time, much if not all of the pain disappears except with certain activities. Some patients will have the tear become asymptomatic for a time, especially if their activity level decreases significantly.

There are a few signs of meniscal tears that can sometimes be elicited. Tenderness is elicited by deep palpation along the joint line. Twisting the knee while flexing it will occasionally cause or reproduce the patient’s symptoms. Meniscal tears do not show up on plain x-rays because the meniscus does not contain calcium the way bones do. There are some specialized tests such as the MRI scan which are helpful in further evaluating the meniscus, although like most medical tests, they cannot be relied upon with 100% confidence. In fact, several recent studies prove that the MRI scan is not as accurate as a good clinical history and physical exam by a specialist.

Natural History: (What happens with no treatment)
Some meniscal tears, especially in relatively inactive people, will go on to become asymptomatic. This is particularly true in older patients. Unfortunately, for many people the symptoms do not go away completely and may actually worsen over time. This may actually be due to a worsening of the tear. The knee can occasionally “lock up” on the patient, preventing them from bending or straightening the knee. Few meniscal tears will heal on their own in the way that an ankle sprain, for instance, will. Only very small tears that are in the periphery of the meniscal tissue, and usually only in young patients, will heal on their own. Those tears associated with an unstable knee, such as when a ligament injury occurs, have a poorer prognosis due to their risk of re-injury.

Treatment Options:
As noted above, some meniscal tears will heal on their own, although this is relatively rare. Treatment must be individualized according to the symptoms and the patient’s activity level. Some patients can live with a meniscal tear without significant worsening over time and need have nothing done after the initial recovery phase. Others will not be able to function at their pre-injury level without treatment. There is no known medicine or therapy that will heal or “fix” a torn meniscus. It is a mechanical problem that often requires a mechanical solution. This usually means either partial excision or repair of the tear. Excision vs repair is often decided at the time of arthroscopic surgery and will depend upon several factors. The patient’s age, the age of the tear, the size and location, as well as the patient’s activity level all play a role in deciding whether a tear can be repaired or must be excised. In general, due to the essential role of the meniscus in protecting the knee from early arthritis, repair is always preferable to removal.

Surgical Intervention:
Once it has been decided by the patient that the best option is a surgical one, the procedure is scheduled. It is performed on an “outpatient” basis (meaning no overnight hospital stay), and it is performed arthroscopically. (See Appendix A concerning general information on arthroscopic surgery.) The knee is systematically evaluated using the arthroscope and the nature of the problem is clarified. Treatment for the problem is then accomplished at that time. If the meniscal tear can be repaired, small stitches or absorbable screws are placed across the tear through the arthroscope. If the tear is not repairable, the minimal amount of meniscus possible is removed so that a smooth, stable surface remains. Occasionally other types of problems are found at the time of arthroscopy such as cartilage damage or fragments of bone or cartilage. These can also be treated at that time. The patient does not feel any pain during the surgery. A videotape is frequently made during the procedure of the important findings and a copy is made for the patient for subsequent review. The procedure usually takes about 30 minutes, although this varies with the complexity of the procedure. The risks of the procedure include those of routine knee arthroscopy (see Appendix A) and, in addition, some added risks if the meniscus is repaired. Most clinical studies indicate that even in the best of circumstances there is still up to a 20% failure rate of the meniscus healing. This might mean a second arthroscopy many months later to remove the unhealed meniscal tear. Despite this potential failure rate, it is best when possible to try to repair all meniscal tears that are reasonable candidates for healing.

If a meniscal repair has been performed, a knee brace is worn for a period after surgery while walking. The knee is carefully rehabilitated in therapy with a progressive program of exercises so that the patient can return as quickly as possible to activities and sports. If no meniscal repair was performed, no knee brace is necessary and the recovery period is shortened. If a large amount of meniscal tissue is lost, there is a significant potential for the development of arthritis in the knee due to increased wear of the cartilage. This can take many years to develop but unfortunately, is inevitable in many patients. It is for this reason that it is so important to repair the meniscal tear if possible. The long-term outcome of meniscal repair and/or partial meniscal excision is quite good. Most patients have few limitations and return to participation in most, if not all, of their pre-injury activities.